The present proposal is a request for funds to purchase a phosphorimager to be used by eight laboratory groups at the Whitehead Institute for Biomedical Research, affiliated with the MIT Dept. of Biology, both in Cambridge, MA, this application being made under the aegis of the NCRR Shared Instrumentation Grant. The research programs in these laboratories, which involve in aggregate approximately 105 research personnel, address problems ranging from the characterizing of genes governing early chordate embryogenesis to the genetic determinants of oncogenesis and the genetics of the yeast MAP kinase signaling pathway. At present, these laboratories all rely heavily on the analysis of radiolabeled molecules, which have been detected over the past three decades through the use of radioautography, involving thereby the use of X-ray films and developers. Over the past five years, a new type of instrumentation has been perfected that enables radiolabeled molecules to be detector with greater sensitivity (and hence in far less time), with linear response measurement over 5 orders of magnitude, and without the use of X-ray film and associated developing reagents. In addition, and as an alternative, the new instrumentation makes it possible to avoid radiolabeling altogether and instead enables the researcher to detect molecules either labeled with non-radioactive fluorescent dyes or with chemiluminescent substrates. This new technology depends on the use of europium crystals to detected emitted radioactivity and photomultipliers to detect light signals emitted (by non radioactively labeled) biological samples. In addition to offering the prospect of dramatically decreased use of radiolabeled materials and attendant exposures to isotope experience experienced by laboratory personnel, this instrumentation offers the prospect of dramatic decreases in both the expenses and waste products that are entailed by the use of X-ray film and the associated chemicals needed to develop exposed film. The 8 laboratory groups which are prospective users of this instrument spend an aggregate $72,000 yearly on autoradiographic supplies and equipment, much of which expense would be obviated by the proposed instrument.